preston



(No Model.) D. R. PRESTON.

PLATFORM ADJUSTMENT FOB; HARVESTERS. No. 278,596. Patee'd May 29,1883.

any c A ENT OFF CE.

DAVID nqrnns'romor WHITEWATER, WISCONSIN.

PLATFORM ADJUSTMENT EOR HARVESTERS.

SPECIFICATIONforming part of Letters Patent No. 278,596, dated May 29, 1883.

i Application filed February 6, 1883. tNo model.) i I l h b To all whom 'it may concern;

/ vesters in which the main frame israised and lowered in relation to the main or ground wheel by means of pinions secured to the ends of its axle, and arranged to engage with upright slottedrack plates secured to the frame, the wheel beingloose on the axle. Heretofore the rotation of the axle and adjusting-pinions has commonly been effected by providing the axle with a drum or pulley, and cxtendin g a chain from one side thereof to a windingdrnm on the main frame. My invention consists in passing a chain around and from opposite sides of the pulley on the axle to opposite sides of awinding-drum, which is made of conical or helical form to compensatefor the varying length of the chain.

Referring to the accompanying drawings, Figure l is a perspective view of the main frame and its connections constructed on my plan; Fig.2, an end view of the winding-drum; Fig. 3, a front elevation of the same, and Fig. 4 a diagramillustrating the relation ofthe various parts.

A represents the main frame, of rectangular form, constructed in the manner described in slots of the rackfplates.

E'represents one of the pinionssecured on the ends of the axle,and engaging with the respectivie rack-plates, so that as the axle is turned in one direction or the other the pinions, acting on said racks, will raise or lower the frame.

F represents the drum or pulley secured to the axle as ameansofturning the same.

The foregoing parts are all of substantially the usual forrinand operate in the ordinary manner.

f G represents the operating-chain, passed around the pulley and extended from its op posite sides to opposite sides and ends of the winding-drum B, so that as thedrum is turned it takes up one end of the chain and slackens the other. may be imparted to the pulley, shaft, and pinions in either direction. As usual, the rackplates are curved in the arc of a circle described from the center of the pinion I, which receives motion from a geared rim on the main, wheel and transmits it to the working parts of the machine. The racks being thus curvedfrom a point eccentric to the axis of the winding-drum, it follows that as theframe rises and falls the distance between the drum and the pulley F changes, thus lengthening or shortening'" the chain. To compensate for the variation and keep the chain constantly at the proper tension, one end of the winding-drum is made with a grooved surface, winding graduallyoutward from thecenterin a spiro-conoidal or helical form, as shown. structed with reference to the other parts in such manner that as the frame rises the lower end of the chain is taken up with increasing rapidity, and vice versa. The opposite end of the drum may have a winding-surface of constant diameter, as shown, to take up the upper end of the chain; or, if preferred, both ends of the drum may be made eccentric, so that each will compensate in partfor the changing length of the chain. The precise form or oura ratchet-wheel and a pawl-lever, as shown, adapted to be operated by the driver while in his seat. The connection of the chain to the drum maybe made in any suitable manner; but it is preferred to provide the drum with perforated ears a, and to connect the chain In this manner a positive motion- This surface is con-.

. vature given the drum is not material, the only 1 The drum is preferably mounted,

thereto by means'of eyebolts or hook-bolts passed through said ears, and provided with tightening-nuts on the ends, as shown. "The chain may have links of any suitable form, and the pulley F a surface provided with suitable projections or recesses to interlock therewith.

The present invention is restricted to those matters and things which are hereinafter claimed, and as to all matters which may be described or shown, but-which are not claimed, the right is reserved to make the same the subro jeotof' a separate patent. v

For the purpose of locking the machine positively at the required height, I employ, in conwheel, as shown.

'driveris enabled to unlock the mechanism with his foot, and to retain the same in the unlocked condition while efi'ecting the required adjustment by means of the hand-lever.

Having thus described myinvention, what I claim isv 1, In a harvesting-machine, the elevatingpull'ey, arranged and operating substantially eccentric surface, substantially as described.

2. A winding-drum for the elevating-chain ot a harvester, having one portion ot'its surface of substantially constant diameter and the remaining portion of-variable diameter, substantially as described and shown. I

3. The winding-drum having two grooved ends, one cylindrical and the other of spiro-. conoidal form, substantially as described and shown. 4. The axle, ils pulley and pinions,in combination with the curved rack-plates, the winding-chain, and the eccentrically-located winding-drum, adapted, substantially as described, to maintain aconstant tension on the chain.

5. In a harvester, the combination of the following elements: the main frame and its rackplates curved in the arc of a circle, the main axle, its pinions and pulley, the chain extending from the two edges of the pulley, and a 

